Fuel Cell Electric Aircraft Energy Challenge New Era of Aviation James Dunn Advanced Technology Products Worcester, MA Electric Aircraft Symposium San Fran – May 2007 Cover Sheet… Introduction….

Fuel cells in Aviation Electric UAV’s – Helios-NASA- Aerovironment Auxiliary Power – Boeing APU – Madrid + Electric Airships – HAA – Lockheed Martin Electric Propulsion - Manned aircraft - E-Plane

Aerovironment “HELIOS” UAV Regenerative fuel cell system

High Altitude Airship Solar PV and Fuel Cells

Fuel Cell Powered Glider Electric Glider Fuel Cell Powered Glider

Piloted Fuel Cell Aircraft 2-place Electric DynAero

Benefits of Electric Aircraft Increased Reliability – 1 moving part! Improved Safety QUIET - only propeller noise Improved Comfort and Easy Maintenance No Vibration Reduced life-cycle costs NO EMISSIONS !

Why Fuel Cells High Efficiency – 2.5 X Gasoline Engines (60% vs. 23%) Zero Emissions – Only Water Vapor No odors or fumes Hydrogen Fuel – Sustainable and Renewable High Energy Density – 300 - 600 WH/kg 2-3 X battery density

The Energy Challenge ! Airplane needs 25kW Power @ 100 mph 300 Mi. flight requires 75 kWh of Energy Energy system Weight for 75kWh: - Lead Acid Batteries = 3000 kg - NiMH Batteries = 1500 kg - LiIon Batteries = 600 kg Fuel Cell system (+ 3 kg H2) = 165 kg (Gasoline Equivalent = 100 kg !)

The Challenge – Matching the energy density of Gasoline and IC Engines? Gasoline =13,200 WH/kg @ 20% effic. Net = 2600 WH/kg Best LiIon Batts = 200 WH/kg Still a 13:1 advantage for Gas!! (H2 = 30,000 WH/kg) Issues – Weight, Volume, HEAT, (+$$)

Hurdles & Issues System Weight – Power Density/Effic. Support Components – Power & Weight Hydrogen Storage/Generation System Heat Transfer methods & HEX System Safety Issues – FAA + Ongoing Customer Acceptance Costly Technology

Hydrogen Sources H2 Gas - High Pressure Tank – 5000 psi Liquid Hydrogen – Cryo issues Reformed Gasoline – CO, CO2 Methanol/Ethanol – Direct or reformate Ammonia (dissociated) – high yield Sodium borohydride – safe, costly Magnesium Hydride Other ??

NASA Fuel Cell Study Elements:

Selected Aircraft for Conversion AGA Lafayette III All Carbon Kit - 28’ Wing We/Wo = .31 80 hp. Rotax 912 < 12 kW to Cruise Vne of 180+ kts

Aircraft Modeling for Hydrogen PEM Fuel Cell Motor Conversion NASA GRC MCR01 ULM Kit Plane Airbreathing Systems Analysis Office (NASA GRC) Systems Analysis Branch (NASA LaRC)

MCR01 ULM Fuel Cell Conversion Power Density Technology Sensitivity: PDPMAD = 1.06 kW/kg MCR01/Rotax 912 > 800 nm Range 800 Advanced Technology Fuel Cell Stack Power Density: 2.50 kW/kg Electric Motor Power Density: 2.30 kW/kg PMAD Power Density: 1.06 kW/kg Range = 336 nm 2.3 Gross weight constant at 992 lb limit 2.5 2.0 2.3 1.8 2.1 1.7 1.9 PDStack (kW/kg) PDMotor (kW/kg) 1.7 1.5 1.5 1.3 Applied State-of-the-Art Technology Fuel Cell Stack Power Density: 1.57 kW/kg Electric Motor Power Density: 1.35 kW/kg PMAD Power Density: 1.06 kW/kg Range = 58 nm Further performance gains possible only if PMAD weight is reduced!

MCR01 ULM Fuel Cell Conversion Power Density Technology Sensitivity: PDPMAD = 2.60 kW/kg Advanced Technology Fuel Cell Stack Power Density: 2.50 kW/kg Electric Motor Power Density: 2.30 kW/kg PMAD Power Density: 2.60 kW/kg Range = 644 nm 2.3 2.5 2.3 2.0 2.1 1.8 1.9 1.7 1.7 1.5 PDStack (kW/kg) 1.5 1.3 PDMotor (kW/kg) Gross weight constant at 992 lb limit Diminishing returns on range – The heavy compressed hydrogen tank limits further gains.

Program Objectives Demonstrate viability of Fuel Cell powered electric propelled aircraft Determine the optimum energy source Analyze performance parameters & range Design/develop High efficiency H2 PEM fuel cell Integrate all components into Airframe and Test Provide educational vehicle for students

Basic Schematic of Components

Students at Oshkosh

Energy Distribution

Battery + Fuel Cell System Rqmts. Max Power - Batteries + Fuel Cell 75 kw Bus voltage 270 DC Net Stack power - cont. 17 kw No. of Cells 180 Efficiency 60 % Fuel Cell sys. Wt. (w/sgl.H2 tank) 80 kg Battery + Master Power Xtrol Wt. 50 kg Total Energy System Weight 130 kg

Fuel Cell System target weight Stack (10-18kW) 25 kg Blower (Compressor)+ duct 5 kg Misc. BOP, plumbing, sensors 4 kg HEX System w/Radiators 9 kg DC-DC Up-convertor 7 kg Fuel Cell Controller/mon. 5 kg Dynatech Tank/Reg. 18 kg Mounting + Misc. 5 kg TOTAL fuel Cell System Weight 78 kg

New Lynntech Stack Design Ultrahigh Efficiency (60%) LightWeight – Metal (No Graphite) Bipolar Plates Ambient Air Ops No Compressor No Hydrators

10 kW Fuel Cell Stack DESIGN SPECIFICATIONS 180 cells 300 cm2 active area Generation 3 endplates 10.25 kW @ 16 psia 137 V 75 A 50 ˚C 25 kg (hydrated) 400 W/kg (@ 250 mA/cm2) 720 W/kg (@500 mA/cm2) 18KW

Specific Energy Equivalent Total Fuel Cell System Sgl. Tank - 78 kg System - 1 kg H2 = 24 kWH Net Energy Density = 24/78 = 307 WH/kg Dbl. Tank – 96 kg system – 2 kg H2 = 48 kWH Net Energy Density = 48/96 = 500 WH/kg

Boeing Fuel Cell Glider Activities System Integration Hydrogen storage Liquid to air heat exchanger Batteries Hydrogen delivery/regulation Fuel Cell Stack Power Conditioner, Regulation, Battery charger Motor Controller Motor Fuel Cell Controller Electric controlled propeller Legend Fuel Electricity Liquid Coolant Control Prop Control “Throttle” Outside Air System Lay – out Design Motor and Drive Fuel Cell Systems Compressor Heat exchanger Pumps Controller Battery Controllers and Converters H2 System

Boeing Activities Electrical Subsystem Electrical Subsystem Configuration Power Balance Power Demand Motor & Drive Controllers Converters Power Generation Fuel Cells Battery Ground Auxiliary Power

Safety and Flight Testing Major concern on all new Aircraft Pilot and Airframe issues

Safety and Flight Testing (Whoops – wrong button !)

Energy System Challenges Energy Density Thermal Management Recharge or Refuel Integration of Solar PV Cost Life Reliability

Technology Evolution Area Today Future (2020) Motor/Xtrol 2kw/kg 8-10 kw/kg Fuel Cell Sys. 2kw/kg 5-6 kw/kg Fuel/H2 Storage 7% H2 – Wt. 12-15 % Energy Storage 200 WH/kg 5-800 WH/kg Energy Produced 150 kWH 1000 kWH Range 100 Mi 1000 mi.

Emerging Energy Solutions Advanced Batteries – Lithium Ion + High Density UltraCaps – EEStor – Other NanoStructured Electrodes – 500-2000 WH/kg High Temp Fuel Cells – Higher power density Advanced H2 Storage – New mat’ls + tanks New Energy Gen. Sources - Many

Future Technology Options Airframe Weight reduction Improved Airframe/Propulsion Efficiency Energy/Fuel Storage options Higher Energy Density Storage Techs New Designs with integrated storage Improved Solar PV Design - Integration

Future Electric PAV ?

CarterCopter Hi-Speed Electric GyroCopter